/* Support macros for making weak and strong aliases for symbols,
and for using symbol sets and linker warnings with GNU ld.
- Copyright (C) 1995-2015 Free Software Foundation, Inc.
+ Copyright (C) 1995-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
+ <https://www.gnu.org/licenses/>. */
#ifndef _LIBC_SYMBOLS_H
#define _LIBC_SYMBOLS_H 1
-#define IN_MODULE PASTE_NAME (MODULE_, MODULE_NAME)
-#define IS_IN(lib) (IN_MODULE == MODULE_##lib)
+/* This file is included implicitly in the compilation of every source file,
+ using -include. It includes config.h. */
-/* Returns true if the current module is a versioned library. Versioned
- library names culled from shlib-versions files are assigned a MODULE_*
- value lower than MODULE_LIBS_BEGIN. */
-#define IS_IN_LIB (IN_MODULE > MODULE_LIBS_BEGIN)
-
-#define PASTE_NAME(a,b) PASTE_NAME1 (a,b)
-#define PASTE_NAME1(a,b) a##b
-
-/* This file's macros are included implicitly in the compilation of every
- file in the C library by -imacros.
-
- We include config.h which is generated by configure.
- It should define for us the following symbol:
+/* Enable declarations of GNU extensions, since we are compiling them. */
+#define _GNU_SOURCE 1
+
+#ifdef MODULE_NAME
+
+/* Use `#if IS_IN (module)` to detect what component is being compiled. */
+#define PASTE_NAME1(a,b) a##b
+#define PASTE_NAME(a,b) PASTE_NAME1 (a,b)
+#define IN_MODULE PASTE_NAME (MODULE_, MODULE_NAME)
+#define IS_IN(lib) (IN_MODULE == MODULE_##lib)
+
+/* True if the current module is a versioned library. Versioned
+ library names culled from shlib-versions files are assigned a
+ MODULE_* value greater than MODULE_LIBS_BEGIN. */
+#define IS_IN_LIB (IN_MODULE > MODULE_LIBS_BEGIN)
+
+/* The testsuite, and some other ancillary code, should be compiled against
+ as close an approximation to the installed headers as possible.
+ Defining this symbol disables most internal-use-only declarations
+ provided by this header, and all those provided by other internal
+ wrapper headers. */
+#if IS_IN (testsuite) || defined IS_IN_build || defined __cplusplus
+# define _ISOMAC 1
+#endif
- * HAVE_ASM_SET_DIRECTIVE if we have `.set B, A' instead of `A = B'.
+#else
+/* The generation process for a few files created very early in the
+ build (notably libc-modules.h itself) involves preprocessing this
+ header without defining MODULE_NAME. Under these conditions,
+ internal declarations (especially from config.h) must be visible,
+ but IS_IN should always evaluate as false. */
+# define IS_IN(lib) 0
+# define IS_IN_LIB 0
+# define IN_MODULE (-1)
+#endif
- */
+#ifndef _ISOMAC
/* This is defined for the compilation of all C library code. features.h
tests this to avoid inclusion of stubs.h while compiling the library,
itself is being compiled, or just some generator program. */
#define _LIBC 1
-/* Enable declarations of GNU extensions, since we are compiling them. */
-#define _GNU_SOURCE 1
-/* And we also need the data for the reentrant functions. */
-#define _REENTRANT 1
+/* Some files must be compiled with optimization on. */
+#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
+# error "glibc cannot be compiled without optimization"
+#endif
+
+/* -ffast-math cannot be applied to the C library, as it alters the ABI.
+ Some test components that use -ffast-math are currently not part of
+ IS_IN (testsuite) for technical reasons, so we have a secondary override. */
+#if defined __FAST_MATH__ && !defined TEST_FAST_MATH
+# error "glibc must not be compiled with -ffast-math"
+#endif
#include <config.h>
+/* When PIC is defined and SHARED isn't defined, we are building PIE
+ by default. */
+#if defined PIC && !defined SHARED
+# define BUILD_PIE_DEFAULT 1
+#else
+# define BUILD_PIE_DEFAULT 0
+#endif
+
/* Define this for the benefit of portable GNU code that wants to check it.
Code that checks with #if will not #include <config.h> again, since we've
already done it (and this file is implicitly included in every compile,
# define ASM_LINE_SEP ;
#endif
+#ifndef __attribute_copy__
+/* Provide an empty definition when cdefs.h is not included. */
+# define __attribute_copy__(arg)
+#endif
+
#ifndef __ASSEMBLER__
/* GCC understands weak symbols and aliases; use its interface where
possible, instead of embedded assembly language. */
/* Define ALIASNAME as a strong alias for NAME. */
# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
# define _strong_alias(name, aliasname) \
- extern __typeof (name) aliasname __attribute__ ((alias (#name)));
+ extern __typeof (name) aliasname __attribute__ ((alias (#name))) \
+ __attribute_copy__ (name);
/* This comes between the return type and function name in
a function definition to make that definition weak. */
If weak aliases are not available, this defines a strong alias. */
# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
# define _weak_alias(name, aliasname) \
- extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
+ extern __typeof (name) aliasname __attribute__ ((weak, alias (#name))) \
+ __attribute_copy__ (name);
/* Same as WEAK_ALIAS, but mark symbol as hidden. */
# define weak_hidden_alias(name, aliasname) \
_weak_hidden_alias (name, aliasname)
# define _weak_hidden_alias(name, aliasname) \
extern __typeof (name) aliasname \
- __attribute__ ((weak, alias (#name), __visibility__ ("hidden")));
+ __attribute__ ((weak, alias (#name), __visibility__ ("hidden"))) \
+ __attribute_copy__ (name);
/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined). */
# define weak_extern(symbol) _weak_extern (weak symbol)
# define _weak_extern(expr) _Pragma (#expr)
+/* In shared builds, the expression call_function_static_weak
+ (FUNCTION-SYMBOL, ARGUMENTS) invokes FUNCTION-SYMBOL (an
+ identifier) unconditionally, with the (potentially empty) argument
+ list ARGUMENTS. In static builds, if FUNCTION-SYMBOL has a
+ definition, the function is invoked as before; if FUNCTION-SYMBOL
+ is NULL, no call is performed. */
+# ifdef SHARED
+# define call_function_static_weak(func, ...) func (__VA_ARGS__)
+# else /* !SHARED */
+# define call_function_static_weak(func, ...) \
+ ({ \
+ extern __typeof__ (func) func weak_function; \
+ (func != NULL ? func (__VA_ARGS__) : (void)0); \
+ })
+# endif
#else /* __ASSEMBLER__ */
#endif /* __ASSEMBLER__ */
-/* On some platforms we can make internal function calls (i.e., calls of
- functions not exported) a bit faster by using a different calling
- convention. */
-#ifndef internal_function
-# define internal_function /* empty */
-#endif
-
/* Determine the return address. */
#define RETURN_ADDRESS(nr) \
__builtin_extract_return_addr (__builtin_return_address (nr))
static const char __evoke_link_warning_##symbol[] \
__attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
= msg;
-#define libc_freeres_ptr(decl) \
- __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
- decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
-#define __libc_freeres_fn_section \
- __attribute__ ((section ("__libc_freeres_fn")))
-
-#define libc_freeres_fn(name) \
- static void name (void) __attribute_used__ __libc_freeres_fn_section; \
- text_set_element (__libc_subfreeres, name); \
- static void name (void)
/* A canned warning for sysdeps/stub functions. */
#define stub_warning(name) \
for linking")
#endif
+/* Resource Freeing Hooks:
+
+ Normally a process exits and the OS cleans up any allocated
+ memory. However, when tooling like mtrace or valgrind is monitoring
+ the process we need to free all resources that are part of the
+ process in order to provide the consistency required to track
+ memory leaks.
+
+ A single public API exists and is __libc_freeres(), and this is used
+ by applications like valgrind to freee resouces.
+
+ There are 3 cases:
+
+ (a) __libc_freeres
+
+ In this case all you need to do is define the freeing routine:
+
+ foo.c:
+ libfoo_freeres_fn (foo_freeres)
+ {
+ complex_free (mem);
+ }
+
+ This ensures the function is called at the right point to free
+ resources.
+
+ (b) __libc_freeres_ptr
+
+ The framework for (a) iterates over the list of pointers-to-free
+ in (b) and frees them.
+
+ foo.c:
+ libc_freeres_ptr (static char *foo_buffer);
+
+ Freeing these resources alaways happens last and is equivalent
+ to registering a function that does 'free (foo_buffer)'.
+
+ (c) Explicit lists of free routines to call or objects to free.
+
+ It is the intended goal to remove (a) and (b) which have some
+ non-determinism based on link order, and instead use explicit
+ lists of functions and frees to resolve cleanup ordering issues
+ and make it easy to debug and maintain.
+
+ As of today the following subsystems use (c):
+
+ Per-thread cleanup:
+ * malloc/thread-freeres.c
+
+ libdl cleanup:
+ * dlfcn/dlfreeres.c
+
+ libpthread cleanup:
+ * nptl/nptlfreeres.c
+
+ So if you need any shutdown routines to run you should add them
+ directly to the appropriate subsystem's shutdown list. */
+
+/* Resource pointers to free in libc.so. */
+#define libc_freeres_ptr(decl) \
+ __make_section_unallocated ("__libc_freeres_ptrs, \"aw\", %nobits") \
+ decl __attribute__ ((section ("__libc_freeres_ptrs" __sec_comment)))
+
+/* Resource freeing functions from libc.so go in this section. */
+#define __libc_freeres_fn_section \
+ __attribute__ ((section ("__libc_freeres_fn")))
+
+/* Resource freeing functions for libc.so. */
+#define libc_freeres_fn(name) \
+ static void name (void) __attribute_used__ __libc_freeres_fn_section; \
+ text_set_element (__libc_subfreeres, name); \
+ static void name (void)
+
/* Declare SYMBOL to be TYPE (`function' or `object') of SIZE bytes
alias to ORIGINAL, when the assembler supports such declarations
(such as in ELF).
past the last element in SET. */
#define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
+/* Use symbol_version_reference to specify the version a symbol
+ reference should link to. Use symbol_version or
+ default_symbol_version for the definition of a versioned symbol.
+ The difference is that the latter is a no-op in non-shared
+ builds. */
+#ifdef __ASSEMBLER__
+# define symbol_version_reference(real, name, version) \
+ .symver real, name##@##version
+#else /* !__ASSEMBLER__ */
+# define symbol_version_reference(real, name, version) \
+ __asm__ (".symver " #real "," #name "@" #version)
+#endif
+
#ifdef SHARED
# define symbol_version(real, name, version) \
- _symbol_version(real, name, version)
+ symbol_version_reference(real, name, version)
# define default_symbol_version(real, name, version) \
_default_symbol_version(real, name, version)
# ifdef __ASSEMBLER__
-# define _symbol_version(real, name, version) \
- .symver real, name##@##version
# define _default_symbol_version(real, name, version) \
.symver real, name##@##@##version
# else
-# define _symbol_version(real, name, version) \
- __asm__ (".symver " #real "," #name "@" #version)
# define _default_symbol_version(real, name, version) \
__asm__ (".symver " #real "," #name "@@" #version)
# endif
strong_alias(real, name)
#endif
-#if defined SHARED || defined LIBC_NONSHARED
+#if defined SHARED || defined LIBC_NONSHARED \
+ || (BUILD_PIE_DEFAULT && IS_IN (libc))
# define attribute_hidden __attribute__ ((visibility ("hidden")))
#else
# define attribute_hidden
#define attribute_relro __attribute__ ((section (".data.rel.ro")))
+
+/* Used to disable stack protection in sensitive places, like ifunc
+ resolvers and early static TLS init. */
+#ifdef HAVE_CC_NO_STACK_PROTECTOR
+# define inhibit_stack_protector \
+ __attribute__ ((__optimize__ ("-fno-stack-protector")))
+#else
+# define inhibit_stack_protector
+#endif
+
/* The following macros are used for PLT bypassing within libc.so
(and if needed other libraries similarly).
First of all, you need to have the function prototyped somewhere,
# define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
# define __hidden_asmname2(prefix, name) #prefix name
# define __hidden_ver1(local, internal, name) \
- extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
- extern __typeof (name) __EI_##name \
- __attribute__((alias (__hidden_asmname (#local))))
+ __hidden_ver2 (, local, internal, name)
+# define __hidden_ver2(thread, local, internal, name) \
+ extern thread __typeof (name) __EI_##name \
+ __asm__(__hidden_asmname (#internal)); \
+ extern thread __typeof (name) __EI_##name \
+ __attribute__((alias (__hidden_asmname (#local)))) \
+ __attribute_copy__ (name)
# define hidden_ver(local, name) __hidden_ver1(local, __GI_##name, name);
# define hidden_data_ver(local, name) hidden_ver(local, name)
# define hidden_def(name) __hidden_ver1(__GI_##name, name, name);
# define hidden_data_def(name) hidden_def(name)
+# define hidden_tls_def(name) \
+ __hidden_ver2 (__thread, __GI_##name, name, name);
# define hidden_weak(name) \
__hidden_ver1(__GI_##name, name, name) __attribute__((weak));
# define hidden_data_weak(name) hidden_weak(name)
# define __hidden_nolink1(local, internal, name, version) \
__hidden_nolink2 (local, internal, name, version)
# define __hidden_nolink2(local, internal, name, version) \
- extern __typeof (name) internal __attribute__ ((alias (#local))); \
+ extern __typeof (name) internal __attribute__ ((alias (#local))) \
+ __attribute_copy__ (name); \
__hidden_nolink3 (local, internal, #name "@" #version)
# define __hidden_nolink3(local, internal, vername) \
__asm__ (".symver " #internal ", " vername);
# define hidden_weak(name) hidden_def (name)
# define hidden_ver(local, name) strong_alias (local, __GI_##name)
# define hidden_data_def(name) strong_data_alias (name, __GI_##name)
+# define hidden_tls_def(name) hidden_data_def (name)
# define hidden_data_weak(name) hidden_data_def (name)
# define hidden_data_ver(local, name) strong_data_alias (local, __GI_##name)
# define HIDDEN_JUMPTARGET(name) __GI_##name
# endif
#else
# ifndef __ASSEMBLER__
-# define hidden_proto(name, attrs...)
-# define hidden_tls_proto(name, attrs...)
+# if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
+ && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
+ && !defined NO_HIDDEN
+# define __hidden_proto_hiddenattr(attrs...) \
+ __attribute__ ((visibility ("hidden"), ##attrs))
+# define hidden_proto(name, attrs...) \
+ __hidden_proto (name, , name, ##attrs)
+# define hidden_tls_proto(name, attrs...) \
+ __hidden_proto (name, __thread, name, ##attrs)
+# define __hidden_proto(name, thread, internal, attrs...) \
+ extern thread __typeof (name) name __hidden_proto_hiddenattr (attrs);
+# else
+# define hidden_proto(name, attrs...)
+# define hidden_tls_proto(name, attrs...)
+# endif
# else
# define HIDDEN_JUMPTARGET(name) JUMPTARGET(name)
# endif /* Not __ASSEMBLER__ */
# define hidden_ver(local, name)
# define hidden_data_weak(name)
# define hidden_data_def(name)
+# define hidden_tls_def(name)
# define hidden_data_ver(local, name)
# define hidden_nolink(name, lib, version)
#endif
# endif
# define libc_hidden_ver(local, name) hidden_ver (local, name)
# define libc_hidden_data_def(name) hidden_data_def (name)
+# define libc_hidden_tls_def(name) hidden_tls_def (name)
# define libc_hidden_data_weak(name) hidden_data_weak (name)
# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libc_hidden_weak(name)
# define libc_hidden_ver(local, name)
# define libc_hidden_data_def(name)
+# define libc_hidden_tls_def(name)
# define libc_hidden_data_weak(name)
# define libc_hidden_data_ver(local, name)
#endif
-#if IS_IN (rtld)
+#if IS_IN (rtld) && !defined NO_RTLD_HIDDEN
# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define rtld_hidden_tls_proto(name, attrs...) hidden_tls_proto (name, ##attrs)
# define rtld_hidden_def(name) hidden_def (name)
# define rtld_hidden_weak(name) hidden_weak (name)
# define rtld_hidden_ver(local, name) hidden_ver (local, name)
# define rtld_hidden_data_def(name) hidden_data_def (name)
+# define rtld_hidden_tls_def(name) hidden_tls_def (name)
# define rtld_hidden_data_weak(name) hidden_data_weak (name)
# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define rtld_hidden_weak(name)
# define rtld_hidden_ver(local, name)
# define rtld_hidden_data_def(name)
+# define rtld_hidden_tls_def(name)
# define rtld_hidden_data_weak(name)
# define rtld_hidden_data_ver(local, name)
#endif
# define libm_hidden_weak(name) hidden_weak (name)
# define libm_hidden_ver(local, name) hidden_ver (local, name)
# define libm_hidden_data_def(name) hidden_data_def (name)
+# define libm_hidden_tls_def(name) hidden_tls_def (name)
# define libm_hidden_data_weak(name) hidden_data_weak (name)
# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libm_hidden_weak(name)
# define libm_hidden_ver(local, name)
# define libm_hidden_data_def(name)
+# define libm_hidden_tls_def(name)
# define libm_hidden_data_weak(name)
# define libm_hidden_data_ver(local, name)
#endif
# define libmvec_hidden_weak(name) hidden_weak (name)
# define libmvec_hidden_ver(local, name) hidden_ver (local, name)
# define libmvec_hidden_data_def(name) hidden_data_def (name)
+# define libmvec_hidden_tls_def(name) hidden_tls_def (name)
# define libmvec_hidden_data_weak(name) hidden_data_weak (name)
# define libmvec_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libmvec_hidden_weak(name)
# define libmvec_hidden_ver(local, name)
# define libmvec_hidden_data_def(name)
+# define libmvec_hidden_tls_def(name)
# define libmvec_hidden_data_weak(name)
# define libmvec_hidden_data_ver(local, name)
#endif
# define libresolv_hidden_weak(name) hidden_weak (name)
# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
# define libresolv_hidden_data_def(name) hidden_data_def (name)
+# define libresolv_hidden_tls_def(name) hidden_tls_def (name)
# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libresolv_hidden_weak(name)
# define libresolv_hidden_ver(local, name)
# define libresolv_hidden_data_def(name)
+# define libresolv_hidden_tls_def(name)
# define libresolv_hidden_data_weak(name)
# define libresolv_hidden_data_ver(local, name)
#endif
# define librt_hidden_weak(name) hidden_weak (name)
# define librt_hidden_ver(local, name) hidden_ver (local, name)
# define librt_hidden_data_def(name) hidden_data_def (name)
+# define librt_hidden_tls_def(name) hidden_tls_def (name)
# define librt_hidden_data_weak(name) hidden_data_weak (name)
# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define librt_hidden_weak(name)
# define librt_hidden_ver(local, name)
# define librt_hidden_data_def(name)
+# define librt_hidden_tls_def(name)
# define librt_hidden_data_weak(name)
# define librt_hidden_data_ver(local, name)
#endif
# define libdl_hidden_weak(name) hidden_weak (name)
# define libdl_hidden_ver(local, name) hidden_ver (local, name)
# define libdl_hidden_data_def(name) hidden_data_def (name)
+# define libdl_hidden_tls_def(name) hidden_tls_def (name)
# define libdl_hidden_data_weak(name) hidden_data_weak (name)
# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libdl_hidden_weak(name)
# define libdl_hidden_ver(local, name)
# define libdl_hidden_data_def(name)
+# define libdl_hidden_tls_def(name)
# define libdl_hidden_data_weak(name)
# define libdl_hidden_data_ver(local, name)
#endif
# define libnss_files_hidden_weak(name) hidden_weak (name)
# define libnss_files_hidden_ver(local, name) hidden_ver (local, name)
# define libnss_files_hidden_data_def(name) hidden_data_def (name)
+# define libnss_files_hidden_tls_def(name) hidden_tls_def (name)
# define libnss_files_hidden_data_weak(name) hidden_data_weak (name)
# define libnss_files_hidden_data_ver(local, name) hidden_data_ver(local, name)
#else
# define libnss_files_hidden_weak(name)
# define libnss_files_hidden_ver(local, name)
# define libnss_files_hidden_data_def(name)
+# define libnss_files_hidden_tls_def(name)
# define libnss_files_hidden_data_weak(name)
# define libnss_files_hidden_data_ver(local, name)
#endif
# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libnsl_hidden_tls_proto(name, attrs...) \
hidden_tls_proto (name, ##attrs)
+# ifdef LINK_OBSOLETE_NSL
+ /* libnsl_hidden_nolink should only get used in libnsl code. */
+# define libnsl_hidden_nolink_def(name, version) libnsl_hidden_def (name)
+# else
+# define libnsl_hidden_nolink_def(name, version) hidden_nolink (name, libnsl, version)
+# endif
# define libnsl_hidden_def(name) hidden_def (name)
# define libnsl_hidden_weak(name) hidden_weak (name)
# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
# define libnsl_hidden_data_def(name) hidden_data_def (name)
+# define libnsl_hidden_tls_def(name) hidden_tls_def (name)
# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libnsl_hidden_weak(name)
# define libnsl_hidden_ver(local, name)
# define libnsl_hidden_data_def(name)
+# define libnsl_hidden_tls_def(name)
# define libnsl_hidden_data_weak(name)
# define libnsl_hidden_data_ver(local, name)
#endif
# define libnss_nisplus_hidden_weak(name) hidden_weak (name)
# define libnss_nisplus_hidden_ver(local, name) hidden_ver (local, name)
# define libnss_nisplus_hidden_data_def(name) hidden_data_def (name)
+# define libnss_nisplus_hidden_tls_def(name) hidden_tls_def (name)
# define libnss_nisplus_hidden_data_weak(name) hidden_data_weak (name)
# define libnss_nisplus_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libnss_nisplus_hidden_weak(name)
# define libnss_nisplus_hidden_ver(local, name)
# define libnss_nisplus_hidden_data_def(name)
+# define libnss_nisplus_hidden_tls_def(name)
# define libnss_nisplus_hidden_data_weak(name)
# define libnss_nisplus_hidden_data_ver(local, name)
#endif
# define libutil_hidden_weak(name) hidden_weak (name)
# define libutil_hidden_ver(local, name) hidden_ver (local, name)
# define libutil_hidden_data_def(name) hidden_data_def (name)
+# define libutil_hidden_tls_def(name) hidden_tls_def (name)
# define libutil_hidden_data_weak(name) hidden_data_weak (name)
# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libutil_hidden_weak(name)
# define libutil_hidden_ver(local, name)
# define libutil_hidden_data_def(name)
+# define libutil_hidden_tls_def(name)
# define libutil_hidden_data_weak(name)
# define libutil_hidden_data_ver(local, name)
#endif
# define compat_data_section .section ".data.compat", "aw";
#endif
-/* Marker used for indirection function symbols. */
-#define libc_ifunc(name, expr) \
- extern void *name##_ifunc (void) __asm__ (#name); \
- void *name##_ifunc (void) \
+/* Helper / base macros for indirect function symbols. */
+#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
+ classifier inhibit_stack_protector \
+ __typeof (type_name) *name##_ifunc (arg) \
{ \
- INIT_ARCH (); \
- __typeof (name) *res = expr; \
+ init (); \
+ __typeof (type_name) *res = expr; \
return res; \
- } \
- __asm__ (".type " #name ", %gnu_indirect_function");
+ }
-/* The body of the function is supposed to use __get_cpu_features
- which will, if necessary, initialize the data first. */
-#define libm_ifunc(name, expr) \
- extern void *name##_ifunc (void) __asm__ (#name); \
- void *name##_ifunc (void) \
- { \
- __typeof (name) *res = expr; \
- return res; \
- } \
- __asm__ (".type " #name ", %gnu_indirect_function");
-
-#ifdef HAVE_ASM_SET_DIRECTIVE
-# define libc_ifunc_hidden_def1(local, name) \
- __asm__ (".globl " #local "\n\t" \
- ".hidden " #local "\n\t" \
- ".set " #local ", " #name);
+#ifdef HAVE_GCC_IFUNC
+# define __ifunc(type_name, name, expr, arg, init) \
+ extern __typeof (type_name) name __attribute__ \
+ ((ifunc (#name "_ifunc"))); \
+ __ifunc_resolver (type_name, name, expr, arg, init, static)
+
+# define __ifunc_hidden(type_name, name, expr, arg, init) \
+ __ifunc (type_name, name, expr, arg, init)
#else
-# define libc_ifunc_hidden_def1(local, name) \
- __asm__ (".globl " #local "\n\t" \
- ".hidden " #local "\n\t" \
- #local " = " #name);
-#endif
+/* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour
+ as fallback. But keep in mind that the debug information for the ifunc
+ resolver functions is not correct. It contains the ifunc'ed function as
+ DW_AT_linkage_name. E.g. lldb uses this field and an inferior function
+ call of the ifunc'ed function will fail due to "no matching function for
+ call to ..." because the ifunc'ed function and the resolver function have
+ different signatures. (Gcc support is disabled at least on a ppc64le
+ Ubuntu 14.04 system.) */
+
+# define __ifunc(type_name, name, expr, arg, init) \
+ extern __typeof (type_name) name; \
+ __typeof (type_name) *name##_ifunc (arg) __asm__ (#name); \
+ __ifunc_resolver (type_name, name, expr, arg, init,) \
+ __asm__ (".type " #name ", %gnu_indirect_function");
+
+# define __ifunc_hidden(type_name, name, expr, arg, init) \
+ extern __typeof (type_name) __libc_##name; \
+ __ifunc (type_name, __libc_##name, expr, arg, init) \
+ strong_alias (__libc_##name, name);
+#endif /* !HAVE_GCC_IFUNC */
+
+/* The following macros are used for indirect function symbols in libc.so.
+ First of all, you need to have the function prototyped somewhere,
+ say in foo.h:
+
+ int foo (int __bar);
+
+ If you have an implementation for foo which e.g. uses a special hardware
+ feature which isn't available on all machines where this libc.so will be
+ used but decideable if available at runtime e.g. via hwcaps, you can provide
+ two or multiple implementations of foo:
+
+ int __foo_default (int __bar)
+ {
+ return __bar;
+ }
+
+ int __foo_special (int __bar)
+ {
+ return __bar;
+ }
+
+ If your function foo has no libc_hidden_proto (foo) defined for PLT
+ bypassing, you can use:
+
+ #define INIT_ARCH() unsigned long int hwcap = __GLRO(dl_hwcap);
+
+ libc_ifunc (foo, (hwcap & HWCAP_SPECIAL) ? __foo_special : __foo_default);
+
+ This will define a resolver function for foo which returns __foo_special or
+ __foo_default depending on your specified expression. Please note that you
+ have to define a macro function INIT_ARCH before using libc_ifunc macro as
+ it is called by the resolver function before evaluating the specified
+ expression. In this example it is used to prepare the hwcap variable.
+ The resolver function is assigned to an ifunc'ed symbol foo. Calls to foo
+ from inside or outside of libc.so will be indirected by a PLT call.
-#define libc_ifunc_hidden_def(name) \
- libc_ifunc_hidden_def1 (__GI_##name, name)
+ If your function foo has a libc_hidden_proto (foo) defined for PLT bypassing
+ and calls to foo within libc.so should always go to one specific
+ implementation of foo e.g. __foo_default then you have to add:
+
+ __hidden_ver1 (__foo_default, __GI_foo, __foo_default);
+
+ or a tweaked definition of libc_hidden_def macro after the __foo_default
+ function definition. Calls to foo within libc.so will always go directly to
+ __foo_default. Calls to foo from outside libc.so will be indirected by a
+ PLT call to ifunc'ed symbol foo which you have to define in a separate
+ compile unit:
+
+ #define foo __redirect_foo
+ #include <foo.h>
+ #undef foo
+
+ extern __typeof (__redirect_foo) __foo_default attribute_hidden;
+ extern __typeof (__redirect_foo) __foo_special attribute_hidden;
+
+ libc_ifunc_redirected (__redirect_foo, foo,
+ (hwcap & HWCAP_SPECIAL)
+ ? __foo_special
+ : __foo_default);
+
+ This will define the ifunc'ed symbol foo like above. The redirection of foo
+ in header file is needed to omit an additional defintion of __GI_foo which
+ would end in a linker error while linking libc.so. You have to specify
+ __redirect_foo as first parameter which is used within libc_ifunc_redirected
+ macro in conjunction with typeof to define the ifunc'ed symbol foo.
+
+ If your function foo has a libc_hidden_proto (foo) defined and calls to foo
+ within or from outside libc.so should go via ifunc'ed symbol, then you have
+ to use:
+
+ libc_ifunc_hidden (foo, foo,
+ (hwcap & HWCAP_SPECIAL)
+ ? __foo_special
+ : __foo_default);
+ libc_hidden_def (foo)
+
+ The first parameter foo of libc_ifunc_hidden macro is used in the same way
+ as for libc_ifunc_redirected macro. */
+
+#define libc_ifunc(name, expr) __ifunc (name, name, expr, void, INIT_ARCH)
+
+#define libc_ifunc_redirected(redirected_name, name, expr) \
+ __ifunc (redirected_name, name, expr, void, INIT_ARCH)
+
+#define libc_ifunc_hidden(redirected_name, name, expr) \
+ __ifunc_hidden (redirected_name, name, expr, void, INIT_ARCH)
+
+/* The body of the function is supposed to use __get_cpu_features
+ which will, if necessary, initialize the data first. */
+#define libm_ifunc_init()
+#define libm_ifunc(name, expr) \
+ __ifunc (name, name, expr, void, libm_ifunc_init)
/* Add the compiler optimization to inhibit loop transformation to library
calls. This is used to avoid recursive calls in memset and memmove
#else
# define inhibit_loop_to_libcall
#endif
+\f
+/* These macros facilitate sharing source files with gnulib.
+
+ They are here instead of sys/cdefs.h because they should not be
+ used in public header files.
+
+ Their definitions should be kept consistent with the definitions in
+ gnulib-common.m4, but it is not necessary to cater to old non-GCC
+ compilers, since they will only be used while building glibc itself.
+ (Note that _GNUC_PREREQ cannot be used in this file.) */
+
+/* Define as a marker that can be attached to declarations that might not
+ be used. This helps to reduce warnings, such as from
+ GCC -Wunused-parameter. */
+#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
+# define _GL_UNUSED __attribute__ ((__unused__))
+#else
+# define _GL_UNUSED
+#endif
+
+/* gcc supports the "unused" attribute on possibly unused labels, and
+ g++ has since version 4.5. Note to support C++ as well as C,
+ _GL_UNUSED_LABEL should be used with a trailing ; */
+#if !defined __cplusplus || __GNUC__ > 4 \
+ || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
+# define _GL_UNUSED_LABEL _GL_UNUSED
+#else
+# define _GL_UNUSED_LABEL
+#endif
+
+/* The __pure__ attribute was added in gcc 2.96. */
+#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
+# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
+#else
+# define _GL_ATTRIBUTE_PURE /* empty */
+#endif
+
+/* The __const__ attribute was added in gcc 2.95. */
+#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
+# define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
+#else
+# define _GL_ATTRIBUTE_CONST /* empty */
+#endif
+#endif /* !_ISOMAC */
#endif /* libc-symbols.h */
projects / thirdparty / glibc.git / blobdiff